164 THE MICROSCOPE. Nov. 



extensions or feelers, the labial palpi (fig. 5 f), which have 

 each three joints. 



To see the jaws, remove the labrum (fig. 4 r), and also, 

 as has been done in this figure, the gena and man- 

 dible (fig. 4 t, s). All parts thus removed from around 

 the mouth should be mounted in glycerine, and exam- 

 ined under low powers of the microscope. 



The jaws consist of three pairs, — one pair of mandibles 

 (fig. 4 s), and two pairs of maxillfe. In figure 4 the left 

 of the first maxilla is well shown to the reader's right, 

 and some of its divisions are lettered f. g. m. In figure 

 5 the left first maxilla also is shown and some of its 

 divisions are lettered b. c. e. The second pair of max- 

 illa are both shown in figure 4 and the left one is marked 

 n. All these six jaws are biting ones. 



The mandibles (s) lie below the genae (t) and are arti- 

 culated to the epicranium (fig. 4 a) and clypeus (fig. 4 e). 

 They are strong and toothed. 



The first maxillae present a subdivision of the append- 

 ao-es of the body that run through the whole of the 

 classes of the Arthropoda or jointed footed animals. A 

 basal part, the protopodite, and two parts attached to 

 the distal end of this, one nearer ihe middle line of the 

 animal's body (the endopodite) the other farther away 

 from it (the expodite). In the maxilla of the cockroach, 

 protopodite consists of two joints, called respectively the 

 cardo, (fig. 5 b) and stipes (fig. 5 c),— cardo, a hinge; 

 stipes, a log. The endopodite is of two parts, the lacinia 

 (fig. 4 f) on the inner side, the galea (fig. 4 g) on the 

 outer side. Lacinia means a lappet; galea, a helmet. 

 The exopodite is the maxillary palpus (figs. 4 m, and 5 e) 

 with two short basal joints and three longer terminal 

 joints. 



The protodites of the second pair of maxilla? are fused 

 together in the labium with its mentum (fig. 5 r), and 

 submentura(fig. 5 s) already described. The endopodites 



